Geologic Time

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Slide 1: 

Chapter 20: A Trip Through Geologic Time

Chapter 20.1: The Geologic Time Scale : 

Chapter 20.1: The Geologic Time Scale 4 Geologic Eras: Precambrian Era Paleozoic Era Mesozoic Era Cenozoic Era An era is the largest division of the geologic time scale Eras are broken into smaller subdivisions called periods

Precambrian Era : 

Precambrian Era Longest era (4.6 bya- 570 mya) Lasted 4 billion years Accounts for 87% of Earth’s history Algae, jellyfish, corals and clams develop Not much information, why?

Paleozoic Era : 

Paleozoic Era Lasted 345 million years (570 mya- 345 mya) Many volcanoes and mountains form Shallow seas cover parts of continents 1st amphibians, insects, and sharks develop

Mesozoic Era : 

Mesozoic Era Lasted 160 millions years (225 mya-160 mya) 1st dinosaurs and mammals appear 1st flowering plant Dinosaurs and many sea living reptiles die out

Cenozoic Era : 

Cenozoic Era Era in which we now live in for the past 65 million years 1st horses, primates, and human like creatures Wooly mammoths die out, civilization begins

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Slide 8: 

Skulls, from left to right: Homo sapiens (human), Homo neanderthalensis (Neanderthal man), and Australopithecus afarensis (Lucy).

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20.2: Early Earth History : 

20.2: Early Earth History Ancient rocks were formed Can be seen on every continent Beginning of the Precambrain era

The Precambrian Era: Dawn of Life : 

The Precambrian Era: Dawn of Life No sign of life Rain falls and thunder rolls but there are no plants to receive the rain and no animals to hear the thunder for 2.6 billion years

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No life in the seas, only patches of mold Seaweed type plants begin to flourish and produce oxygen which will support life over the next billion years At end of the era, jellyfish, corals, worms, and sponges appear in the seas

The Paleozoic Era: Life Comes Ashore : 

The Paleozoic Era: Life Comes Ashore 570 MYA Land is still lifeless but the seas are full of life Worms crawl across sandy bottom

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Trilobites- Sea animals with large heads, long thorny spines, and many body divisions They evolved rapidly during the era and became extinct at the end of the era Brachiopods- lamp shade shaped shells that lived on the seafloor

Slide 15: 

Fishes can be found almost everywhere 1st animals, or vertebrates with backbones, to appear on Earth Devonion Period- often called the “Age of Fishes”

Pre-Historic Shark Finding : 

Pre-Historic Shark Finding

Slide 19: 

Huge forests of ferns have developed Remains of these forests formed huge coal deposits in the US and other parts of world Amphibians, such as Eryops, appear. They are the 1st land vertebrates.

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Amphibian-”Living a double life”. Spend the early part of the their life in water then move to land Eryops- very large, 6 feet long, waddles through forests in search of giant roaches. Must keep skin moist so stays close to water

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By the end of the Paleozoic Era, there is a drought and the climate has cooled. Mountains start rising in what will become Norway, Scotland, Greenland, and N. America Other landmasses are created and this will be the beginning of Pangaea

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New kinds of animals that live on land all the time are appearing Their tough skin is protected by scales and hard plates These animals do not lose water through their skins They lay eggs and are known as reptiles They will dominate the Earth for the next 160 million years

20-3: Middle & Recent Earth History : 

20-3: Middle & Recent Earth History

Mesozoic Era: Mammals Develop : 

Mesozoic Era: Mammals Develop 226-65 MYA Pangaea began to break apart and many mountains were formed Divided into 3 Periods: Triassic Jurassic Cretaceous

Triassic Period : 

Triassic Period N & S. America separate from Africa, the N. Atlantic Ocean is formed Reptiles- land living animals- return to the sea Mammals are animals with hair or fur, whose offspring, for the most part, do not hatch from eggs

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Young grow and mature in their mother’s body before birth Trees are uprooted by floods 1st dinosaurs are appearing, many are as small as chickens

Jurassic Period : 

Jurassic Period Age of dinosaurs begins Volcanoes are active Southern continents are still linked Evergreens and conifers make up the forests The first bird “Archaeopteryx” appears

Cretaceous Period : 

Cretaceous Period Widespread flooding of continents by seas The continents are still moving apart Tyrannosaurus, the greatest meat eater of all times, stalks the land

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Triceratops- armored plant eating dinosaur At the end of the period all dinosaurs and sea living reptiles will become extinct Only crocodiles, turtles, lizards and snakes will have survived

Slide 30: 

Science debates on what the extinction was caused from: Change in climate A worldwide disease Gigantic asteroid Sea levels dropped River and flood plains, where dinosaurs thrived, dried up

Slide 31: 

Flowing plants appeared As new plant life spread, most great tree ferns died out The world was taking on a look that is familiar to us today

Cenozoic Era: A World With People : 

Cenozoic Era: A World With People 65 MYA to present Evolution of first horses and first animals to walk on two feet Ice sheets will sweep across land Modern day humans evolve 

Tertiary Period : 

Tertiary Period Groups of redwoods, oaks, cedars, and palm trees Climate is mild Uintatherium, was a strange looking beast that resembled a rhinoceros and an elephant

Slide 34: 

3.4 MYA, human like creatures begin walking upright in the African plains “Lucy” will be discovered in 1977 and is 3 feet tall.

Quaternary Period : 

Quaternary Period The climate gets extremely cold Giant ice sheets move several times from the Artic to the Antarctic The last ice age ends 11,000 As the world warms, farming becomes widespread and modern civilization begins

20.4: Evolution Over Time : 

20.4: Evolution Over Time

Evolution : 

Evolution Means unfolding or opening out Descent- To come from something that lived before Modification- To change Evolution- All inhabitants of Earth are changed forms of living things that came before

Slide 39: 

A change in species over time Species- group of organisms that share similar characteristics and that can interbreed with one another to produce fertile offspring Lions and tigers are a species, and they can breed to produce ligers and tiglons The offspring, however, are not fertile and can’t produce more of their own kind

Questions? : 

Questions? Q: Why have some species evolved into the plants and animals living on Earth today while other species became extinct?? A: Changes in the genes of organisms have produced new or slightly modified living things.

Slide 41: 

A gene is a unit of heredity that is passed on from parent to offspring. A change in a gene will produce a change in the offspring of an organism Changes in genes are called mutations Mutations are one of the driving forces behind evolution

Mutations: Agents of Change : 

Mutations: Agents of Change Produces an organism that cannot compete with other organisms. The new organism usually dies off quickly However, sometimes the change is a positive one

Adaptation : 

Adaptation Change that makes the organism better suited to its environment A change that increases an organism’s chances of survival They are able to produce offspring

Slide 44: 

New species may no longer resemble its ancient ancestors The new species may become so successful in its environment that the species from which it evolved can no longer compete and original species dies off New species can result in the extinction of another species

Slide 45: 

Examples of Adaptations: A hummingbirds beak Giraffe’s neck Vampires teeth Monkeys aposable thumb Penguins skin Fish fins

The Fossil Record : 

The Fossil Record Provides evidence about the changes that have occurred in living things and their way of life The fossil record is incomplete because many organisms have come and gone without leaving any fossils

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